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    <title>Base64编码加密</title>
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<table width="773" border="0" align="center" cellpadding="0" cellspacing="0">
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        <td>
            <script language=javascript>
                var base64EncodeChars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
                var base64DecodeChars = new Array(
                        -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
                        -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
                        -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 62, -1, -1, -1, 63,
                        52, 53, 54, 55, 56, 57, 58, 59, 60, 61, -1, -1, -1, -1, -1, -1,
                        -1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14,
                        15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, -1, -1, -1, -1, -1,
                        -1, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40,
                        41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, -1, -1, -1, -1, -1);
                function base64encode(str) {
                    var out, i, len;
                    var c1, c2, c3;
                    len = str.length;
                    i = 0;
                    out = "";
                    while (i < len) {
                        c1 = str.charCodeAt(i++) & 0xff;
                        if (i == len) {
                            out += base64EncodeChars.charAt(c1 >> 2);
                            out += base64EncodeChars.charAt((c1 & 0x3) << 4);
                            out += "==";
                            break;
                        }
                        c2 = str.charCodeAt(i++);
                        if (i == len) {
                            out += base64EncodeChars.charAt(c1 >> 2);
                            out += base64EncodeChars.charAt(((c1 & 0x3) << 4) | ((c2 & 0xF0) >> 4));
                            out += base64EncodeChars.charAt((c2 & 0xF) << 2);
                            out += "=";
                            break;
                        }
                        c3 = str.charCodeAt(i++);
                        out += base64EncodeChars.charAt(c1 >> 2);
                        out += base64EncodeChars.charAt(((c1 & 0x3) << 4) | ((c2 & 0xF0) >> 4));
                        out += base64EncodeChars.charAt(((c2 & 0xF) << 2) | ((c3 & 0xC0) >> 6));
                        out += base64EncodeChars.charAt(c3 & 0x3F);
                    }
                    return out;
                }
                function base64decode(str) {
                    var c1, c2, c3, c4;
                    var i, len, out;
                    len = str.length;
                    i = 0;
                    out = "";
                    while (i < len) {
                        /* c1 */
                        do {
                            c1 = base64DecodeChars[str.charCodeAt(i++) & 0xff];
                        } while (i < len && c1 == -1);
                        if (c1 == -1)
                            break;
                        /* c2 */
                        do {
                            c2 = base64DecodeChars[str.charCodeAt(i++) & 0xff];
                        } while (i < len && c2 == -1);
                        if (c2 == -1)
                            break;
                        out += String.fromCharCode((c1 << 2) | ((c2 & 0x30) >> 4));
                        /* c3 */
                        do {
                            c3 = str.charCodeAt(i++) & 0xff;
                            if (c3 == 61)
                                return out;
                            c3 = base64DecodeChars[c3];
                        } while (i < len && c3 == -1);
                        if (c3 == -1)
                            break;
                        out += String.fromCharCode(((c2 & 0XF) << 4) | ((c3 & 0x3C) >> 2));
                        /* c4 */
                        do {
                            c4 = str.charCodeAt(i++) & 0xff;
                            if (c4 == 61)
                                return out;
                            c4 = base64DecodeChars[c4];
                        } while (i < len && c4 == -1);
                        if (c4 == -1)
                            break;
                        out += String.fromCharCode(((c3 & 0x03) << 6) | c4);
                    }
                    return out;
                }
                function utf16to8(str) {
                    var out, i, len, c;
                    out = "";
                    len = str.length;
                    for (i = 0; i < len; i++) {
                        c = str.charCodeAt(i);
                        if ((c >= 0x0001) && (c <= 0x007F)) {
                            out += str.charAt(i);
                        } else if (c > 0x07FF) {
                            out += String.fromCharCode(0xE0 | ((c >> 12) & 0x0F));
                            out += String.fromCharCode(0x80 | ((c >> 6) & 0x3F));
                            out += String.fromCharCode(0x80 | ((c >> 0) & 0x3F));
                        } else {
                            out += String.fromCharCode(0xC0 | ((c >> 6) & 0x1F));
                            out += String.fromCharCode(0x80 | ((c >> 0) & 0x3F));
                        }
                    }
                    return out;
                }
                function utf8to16(str) {
                    var out, i, len, c;
                    var char2, char3;
                    out = "";
                    len = str.length;
                    i = 0;
                    while (i < len) {
                        c = str.charCodeAt(i++);
                        switch (c >> 4) {
                            case 0:
                            case 1:
                            case 2:
                            case 3:
                            case 4:
                            case 5:
                            case 6:
                            case 7:
                                // 0xxxxxxx
                                out += str.charAt(i - 1);
                                break;
                            case 12:
                            case 13:
                                // 110x xxxx   10xx xxxx
                                char2 = str.charCodeAt(i++);
                                out += String.fromCharCode(((c & 0x1F) << 6) | (char2 & 0x3F));
                                break;
                            case 14:
                                // 1110 xxxx  10xx xxxx  10xx xxxx
                                char2 = str.charCodeAt(i++);
                                char3 = str.charCodeAt(i++);
                                out += String.fromCharCode(((c & 0x0F) << 12) |
                                        ((char2 & 0x3F) << 6) |
                                        ((char3 & 0x3F) << 0));
                                break;
                        }
                    }
                    return out;
                }
                function doit() {
                    var f = document.f
                    f.output.value = base64encode(utf16to8(f.source.value))
                    f.decode.value = utf8to16(base64decode(f.output.value))
                }
            </script>
            <H1 align="center">Base64编码加密
            </H1>

            <FORM NAME="f">
                原码<BR>
                <TEXTAREA NAME="source" ROWS=4 COLS=60 WRAP="soft"></TEXTAREA><BR><BR>
                Base64 encode<BR>
                <TEXTAREA NAME="output" ROWS=4 COLS=60 WRAP="soft"></TEXTAREA><BR><BR>
                Base64 decode<BR>
                <TEXTAREA NAME="decode" ROWS=4 COLS=60 WRAP="soft"></TEXTAREA><BR><BR>
                <INPUT TYPE=BUTTON VALUE="转换" ONCLICK="doit()">
            </FORM>
        </td>
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